This invention relates to a biorhythm calculator, and more particularly to a readily manipulated biorhythm calculator capable of accurately and stably observing critical days which, on the basis of a biorhythm calendar prepared by the same inventor as for this application, consist of a cycle and a semi-cycle at a periodic change in body and mind conditions such as physical, sensitive or emotional, and intellectual states.
Conventionally, critical days in the biorhythmical conditions have been calculated in such a manner that three values of physical, sensitive, and intellectual on the first day of one's biorhythmical condition to be found are calculated by simple addition and substraction based on the date of one's birth and use of a biorhythm table indicative of biorhythmics. This calculation has been considered as convenient if biorhythm conditions throughout one month are plotted on a calendar by use of a specific indicia scale for biorhythm but involves difficulty in that the scale must be graduated in biorhythmic values other than the date so that various values other than what is plotted on the calendar must be calculated, and the other values may interfere with the value to be found whereby the operator cannot read the figure. In addition, the variety of values to be calculated renders the scale complicated and unreliable in operation. Further, the indicia reference numbers are scattered on the outer surface of the scale and a misalignment of the indicia on the regular scale with those on the vernier may possibly lead the operator to an error in operation and thus to the wrong biorhythm conditions.